This invention relates to cleaning apparatus for cleaning pieces of solid materials such as glass substrates and disk substrates, and more particularly to semiconductor wafer cleaning apparatus.
FIG. 3 shows a vertical section of a conventional semiconductor wafer cleaning apparatus. An ice making unit 1 surrounded by insulating materials is supplied with liquid nitrogen via a liquid nitrogen supply pipe 2. Thus, the interior of the ice making unit 1 is cooled by the evaporation of the liquid nitrogen. After the interior of the ice making unit 1 is cooled sufficiently, ultrapure water is sprayed in fine particles from a spray nozzle 3, such that fine ice particles 4 are produced. The fine ice particles 4 thus produced in the ice making unit 1 are ejected into a cleaning vessel 10 via a jet nozzle 5. The fine ice particles 4 are sprayed under high pressure by means of the ejector method utilizing a jet of a pressurized gas. Thus, by blowing the fine ice particles 4 against the wafer 7 supported by a wafer holder arm 6, the surface of the wafer 7 is cleaned. At the same time, the interior of the cleaning vessel 10 is exhausted via an exhaust blower 9 to prevent the upward flows within the cleaning vessel 10.
The above conventional semiconductor wafer cleaning apparatus, however, has the following disadvantage.
Since all the jetted particles within the cleaning vessel 10 must be drawn into the exhaust duct, a large capacity exhaust blower 9 is required. Thus, the exhaust blower 9 becomes large-sized. On the other hand, if an exhaust blower of small capacity is utilized, it is incapable of complete exhaustion of the jetted particles from the cleaning vessel 10, such that the fine ice particles 4 ejected from the jet nozzle 5 are blown upward together with the dusts to be adhered again to the wafer 7.